[MM3-users] (Email|Thread) matching query does not exist ?

I am seeing these errors:

mailman-suite_project$ python manage.py qcluster
19:27:52 [Q] INFO Q Cluster-11541 starting.
19:27:52 [Q] INFO Process-1:1 ready for work at 11546
19:27:52 [Q] INFO Process-1:2 ready for work at 11547
19:27:52 [Q] INFO Process-1 guarding cluster at 11545
19:27:52 [Q] INFO Process-1:4 pushing tasks at 11549
19:27:52 [Q] INFO Q Cluster-11541 running.
19:27:52 [Q] INFO Process-1:3 monitoring at 11548
19:27:52 [Q] INFO Process-1:1 processing [rebuild_email_cache_votes]
19:27:52 [Q] INFO Process-1:2 processing [rebuild_thread_cache_votes]
19:27:52 [Q] INFO Process-1:1 processing [rebuild_email_cache_votes]
19:27:52 [Q] ERROR Failed [rebuild_email_cache_votes] - Email
matching query does not exist.
19:27:52 [Q] ERROR Failed [rebuild_email_cache_votes] - Email
matching query does not exist.
19:27:52 [Q] ERROR Failed [rebuild_thread_cache_votes] - Thread
matching query does not exist.

Should I need to worry? I recently deleted some test emails from the archive. Don't know if this has anything to do with it.

Simon